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                <h2 id="事件"><a href="#事件" class="headerlink" title="事件"></a>事件</h2><blockquote>
<p>事件的写法都是<code>on</code>开头然后驼峰式命名</p>
</blockquote>
<p>写法1：</p>
<pre class=" language-javascript"><code class="language-javascript"><span class="token operator">&lt;</span>span onClick<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>handleLikedClick<span class="token punctuation">}</span><span class="token operator">></span></code></pre>
<p>然后在外部定义方法即可</p>
<p>写法2：</p>
<pre class=" language-javascript"><code class="language-javascript"><span class="token operator">&lt;</span>span onClick<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>handleLikedClick <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span>
    <span class="token comment" spellcheck="true">// 函数体</span>
<span class="token punctuation">}</span><span class="token punctuation">}</span><span class="token operator">></span></code></pre>
<h3 id="添加内容进入Todos数组"><a href="#添加内容进入Todos数组" class="headerlink" title="添加内容进入Todos数组"></a>添加内容进入Todos数组</h3><p>在父组件中添加<code>addTodo</code>方法</p>
<blockquote>
<p>第一个写法，按照常规思想就是使用数组的<code>push</code>方法将新的内容塞进数组里，就完成了添加操作，在这里是不行的。<code>push</code>操作返回的是数组的长度，而不会返回数组</p>
</blockquote>
<pre class=" language-javascript"><code class="language-javascript">addTodo <span class="token operator">=</span> <span class="token punctuation">(</span>todoTitle<span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span>
    <span class="token comment" spellcheck="true">// 这样写出事了，返回的不是一个数组，push返回的是数组的长度</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">setState</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
      todos<span class="token punctuation">:</span> <span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>todos<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
        id<span class="token punctuation">:</span> Math<span class="token punctuation">.</span><span class="token function">random</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
        title<span class="token punctuation">:</span> todoTitle<span class="token punctuation">,</span>
        isCompleted<span class="token punctuation">:</span> <span class="token boolean">false</span>
      <span class="token punctuation">}</span><span class="token punctuation">)</span>
    <span class="token punctuation">}</span><span class="token punctuation">)</span>
  <span class="token punctuation">}</span></code></pre>
<blockquote>
<p>这是第二个写法，这里使用<code>concat</code>方法进行新增</p>
</blockquote>
<pre class=" language-javascript"><code class="language-javascript">addTodo <span class="token operator">=</span> <span class="token punctuation">(</span>todoTitle<span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span>
    <span class="token comment" spellcheck="true">// 这是正确的写法</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">setState</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
      todos<span class="token punctuation">:</span> <span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>todos<span class="token punctuation">.</span><span class="token function">concat</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
        id<span class="token punctuation">:</span> Math<span class="token punctuation">.</span><span class="token function">random</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
        title<span class="token punctuation">:</span> todoTitle<span class="token punctuation">,</span>
        isCompleted<span class="token punctuation">:</span> <span class="token boolean">false</span>
      <span class="token punctuation">}</span><span class="token punctuation">)</span>
    <span class="token punctuation">}</span><span class="token punctuation">)</span>
  <span class="token punctuation">}</span></code></pre>
<blockquote>
<p>这是第三个方法，先用数组的<code>slice</code>方法复制一份保存，然后将复制后的进行<code>push</code>操作，最后设置新的数组内容为复制过后新增的数组内容即可</p>
</blockquote>
<pre class=" language-javascript"><code class="language-javascript">addTodo <span class="token operator">=</span> <span class="token punctuation">(</span>todoTitle<span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span>
    <span class="token comment" spellcheck="true">// 复制一份到新的数组</span>
    <span class="token keyword">const</span> newTodos <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>todos<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    newTodos<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
      id<span class="token punctuation">:</span> Math<span class="token punctuation">.</span><span class="token function">random</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
      title<span class="token punctuation">:</span> todoTitle<span class="token punctuation">,</span>
      isCompleted<span class="token punctuation">:</span> <span class="token boolean">false</span>
    <span class="token punctuation">}</span><span class="token punctuation">)</span>

    <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">setState</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
      todos<span class="token punctuation">:</span> newTodos
    <span class="token punctuation">}</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span></code></pre>
<blockquote>
<p>复制数组的第二个方式：</p>
</blockquote>
<pre class=" language-javascript"><code class="language-javascript"><span class="token keyword">const</span> newTodos <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token operator">...</span><span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>todos<span class="token punctuation">]</span><span class="token punctuation">;</span></code></pre>
<blockquote>
<p>父组件调用：</p>
</blockquote>
<pre class=" language-javascript"><code class="language-javascript"><span class="token function">render</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">return</span> <span class="token punctuation">(</span>
        <span class="token operator">&lt;</span>Fragment<span class="token operator">></span>
          <span class="token operator">&lt;</span>TodoHeader desc<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>desc<span class="token punctuation">}</span> x<span class="token operator">=</span><span class="token punctuation">{</span><span class="token number">1</span><span class="token punctuation">}</span> y<span class="token operator">=</span><span class="token punctuation">{</span><span class="token number">2</span><span class="token punctuation">}</span><span class="token operator">></span>
            <span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>title<span class="token punctuation">}</span>
          <span class="token operator">&lt;</span><span class="token operator">/</span>TodoHeader<span class="token operator">></span>

          <span class="token comment" spellcheck="true">// 这里进行调用添加方法</span>
          <span class="token operator">&lt;</span>TodoInput addTodo<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>addTodo<span class="token punctuation">}</span><span class="token operator">/</span><span class="token operator">></span>
          <span class="token operator">&lt;</span>TodoList todos<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>todos<span class="token punctuation">}</span><span class="token operator">/</span><span class="token operator">></span>

          <span class="token operator">&lt;</span>Like<span class="token operator">/</span><span class="token operator">></span>

        <span class="token operator">&lt;</span><span class="token operator">/</span>Fragment<span class="token operator">></span>
    <span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token punctuation">}</span></code></pre>
<p><strong>完整代码</strong></p>
<pre class=" language-javascript"><code class="language-javascript"><span class="token keyword">import</span> React<span class="token punctuation">,</span> <span class="token punctuation">{</span>Component<span class="token punctuation">,</span> Fragment<span class="token punctuation">}</span> <span class="token keyword">from</span> <span class="token string">'react'</span><span class="token punctuation">;</span>
<span class="token keyword">import</span> <span class="token punctuation">{</span>Like<span class="token punctuation">,</span> TodoHeader<span class="token punctuation">,</span> TodoInput<span class="token punctuation">,</span> TodoList<span class="token punctuation">}</span> <span class="token keyword">from</span> <span class="token string">'./components'</span><span class="token punctuation">;</span>

<span class="token keyword">class</span> <span class="token class-name">App</span> <span class="token keyword">extends</span> <span class="token class-name">Component</span> <span class="token punctuation">{</span>
  <span class="token comment" spellcheck="true">// 定义组件的内部值</span>
  <span class="token comment" spellcheck="true">// state = {</span>
  <span class="token comment" spellcheck="true">//   title: '代办事项列表'</span>
  <span class="token comment" spellcheck="true">// }</span>

  <span class="token function">constructor</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">super</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span>state <span class="token operator">=</span> <span class="token punctuation">{</span>
      title<span class="token punctuation">:</span> <span class="token string">'代办事项列表'</span><span class="token punctuation">,</span>
      desc<span class="token punctuation">:</span> <span class="token string">'今日事，今日毕'</span><span class="token punctuation">,</span>
      todos<span class="token punctuation">:</span> <span class="token punctuation">[</span><span class="token punctuation">{</span>
        id<span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">,</span>
        title<span class="token punctuation">:</span> <span class="token string">'吃饭'</span><span class="token punctuation">,</span>
        assignee<span class="token punctuation">:</span> <span class="token string">'wujie'</span><span class="token punctuation">,</span>
        isCompleted<span class="token punctuation">:</span> <span class="token boolean">true</span>
      <span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token punctuation">{</span>
        id<span class="token punctuation">:</span> <span class="token number">2</span><span class="token punctuation">,</span>
        title<span class="token punctuation">:</span> <span class="token string">'睡觉'</span><span class="token punctuation">,</span>
        assignee<span class="token punctuation">:</span> <span class="token string">'virus'</span><span class="token punctuation">,</span>
        isCompleted<span class="token punctuation">:</span> <span class="token boolean">false</span>
      <span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token punctuation">{</span>
        id<span class="token punctuation">:</span> <span class="token number">3</span><span class="token punctuation">,</span>
        title<span class="token punctuation">:</span> <span class="token string">'喝水'</span><span class="token punctuation">,</span>
        assignee<span class="token punctuation">:</span> <span class="token string">'wujiedeyouxi'</span><span class="token punctuation">,</span>
        isCompleted<span class="token punctuation">:</span> <span class="token boolean">false</span>
      <span class="token punctuation">}</span><span class="token punctuation">]</span>
    <span class="token punctuation">}</span>
  <span class="token punctuation">}</span>

  addTodo <span class="token operator">=</span> <span class="token punctuation">(</span>todoTitle<span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span>
    <span class="token comment" spellcheck="true">// 这样写出事了，返回的不是一个数组，push返回的是数组的长度</span>
    <span class="token comment" spellcheck="true">// this.setState({</span>
    <span class="token comment" spellcheck="true">//   todos: this.state.todos.push({</span>
    <span class="token comment" spellcheck="true">//     id: Math.random(),</span>
    <span class="token comment" spellcheck="true">//     title: todoTitle,</span>
    <span class="token comment" spellcheck="true">//     isCompleted: false</span>
    <span class="token comment" spellcheck="true">//   })</span>
    <span class="token comment" spellcheck="true">// })</span>

    <span class="token comment" spellcheck="true">// 这是正确的写法</span>
    <span class="token comment" spellcheck="true">// this.setState({</span>
    <span class="token comment" spellcheck="true">//   todos: this.state.todos.concat({</span>
    <span class="token comment" spellcheck="true">//     id: Math.random(),</span>
    <span class="token comment" spellcheck="true">//     title: todoTitle,</span>
    <span class="token comment" spellcheck="true">//     isCompleted: false</span>
    <span class="token comment" spellcheck="true">//   })</span>
    <span class="token comment" spellcheck="true">// })</span>

    <span class="token comment" spellcheck="true">// 复制一个数组</span>
    <span class="token keyword">const</span> newTodos <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>todos<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token comment" spellcheck="true">// 复制数组的第二个方式</span>
    <span class="token comment" spellcheck="true">// const newTodos = [...this.state.todos];</span>

    newTodos<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
      id<span class="token punctuation">:</span> Math<span class="token punctuation">.</span><span class="token function">random</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
      title<span class="token punctuation">:</span> todoTitle<span class="token punctuation">,</span>
      isCompleted<span class="token punctuation">:</span> <span class="token boolean">false</span>
    <span class="token punctuation">}</span><span class="token punctuation">)</span>

    <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">setState</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
      todos<span class="token punctuation">:</span> newTodos
    <span class="token punctuation">}</span><span class="token punctuation">)</span>
  <span class="token punctuation">}</span>

  <span class="token function">render</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">return</span> <span class="token punctuation">(</span>
        <span class="token operator">&lt;</span>Fragment<span class="token operator">></span>
          <span class="token operator">&lt;</span>TodoHeader desc<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>desc<span class="token punctuation">}</span> x<span class="token operator">=</span><span class="token punctuation">{</span><span class="token number">1</span><span class="token punctuation">}</span> y<span class="token operator">=</span><span class="token punctuation">{</span><span class="token number">2</span><span class="token punctuation">}</span><span class="token operator">></span>
            <span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>title<span class="token punctuation">}</span>
          <span class="token operator">&lt;</span><span class="token operator">/</span>TodoHeader<span class="token operator">></span>
          <span class="token operator">&lt;</span>TodoInput addTodo<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>addTodo<span class="token punctuation">}</span><span class="token operator">/</span><span class="token operator">></span>
          <span class="token operator">&lt;</span>TodoList todos<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>todos<span class="token punctuation">}</span><span class="token operator">/</span><span class="token operator">></span>

          <span class="token operator">&lt;</span>Like<span class="token operator">/</span><span class="token operator">></span>

        <span class="token operator">&lt;</span><span class="token operator">/</span>Fragment<span class="token operator">></span>
    <span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token punctuation">}</span>
<span class="token punctuation">}</span>

<span class="token keyword">export</span> <span class="token keyword">default</span> App<span class="token punctuation">;</span></code></pre>
<hr>
<p><strong><em>TodoInput的组件的添加操作</em></strong></p>
<pre class=" language-javascript"><code class="language-javascript"><span class="token function">render</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">return</span> <span class="token punctuation">(</span>
        <span class="token operator">&lt;</span>div<span class="token operator">></span>
          <span class="token comment" spellcheck="true">// 获取输入的内容</span>
          <span class="token operator">&lt;</span>input type<span class="token operator">=</span><span class="token string">"text"</span> value<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>inputValue<span class="token punctuation">}</span>
                 onChange<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>handleInputChange<span class="token punctuation">}</span>
          <span class="token operator">/</span><span class="token operator">></span>
          <span class="token comment" spellcheck="true">// 绑定添加方法</span>
          <span class="token operator">&lt;</span>button onClick<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>handleAddClick<span class="token punctuation">.</span><span class="token function">bind</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">}</span><span class="token operator">></span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>props<span class="token punctuation">.</span>btnText<span class="token punctuation">}</span><span class="token operator">&lt;</span><span class="token operator">/</span>button<span class="token operator">></span>
        <span class="token operator">&lt;</span><span class="token operator">/</span>div<span class="token operator">></span>
    <span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token punctuation">}</span></code></pre>
<blockquote>
<p>方法中调用父组件的添加方法，将获取的输入的内容传入参数</p>
</blockquote>
<pre class=" language-javascript"><code class="language-javascript">handleAddClick <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span>props<span class="token punctuation">.</span><span class="token function">addTodo</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>inputValue<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span></code></pre>
<p><strong>完整代码</strong></p>
<pre class=" language-javascript"><code class="language-javascript"><span class="token keyword">import</span> React<span class="token punctuation">,</span> <span class="token punctuation">{</span>Component<span class="token punctuation">}</span> <span class="token keyword">from</span> <span class="token string">'react'</span><span class="token punctuation">;</span>
<span class="token keyword">import</span> PropTypes <span class="token keyword">from</span> <span class="token string">'prop-types'</span><span class="token punctuation">;</span>

<span class="token keyword">class</span> <span class="token class-name">TodoInput</span> <span class="token keyword">extends</span> <span class="token class-name">Component</span> <span class="token punctuation">{</span>
  <span class="token comment" spellcheck="true">// 静态的对象</span>
  <span class="token keyword">static</span> propTypes <span class="token operator">=</span> <span class="token punctuation">{</span>
    btnText<span class="token punctuation">:</span> PropTypes<span class="token punctuation">.</span>string
  <span class="token punctuation">}</span>

  <span class="token comment" spellcheck="true">/**
   * 组件的默认值
   * @type {{btnText: string}}
   */</span>
  <span class="token keyword">static</span> defaultProps <span class="token operator">=</span> <span class="token punctuation">{</span>
    btnText<span class="token punctuation">:</span> <span class="token string">'添加TODO'</span>
  <span class="token punctuation">}</span>

  <span class="token function">constructor</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">super</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span>state <span class="token operator">=</span> <span class="token punctuation">{</span>
      inputValue<span class="token punctuation">:</span> <span class="token string">''</span>
    <span class="token punctuation">}</span>
  <span class="token punctuation">}</span>

  handleInputChange <span class="token operator">=</span> <span class="token punctuation">(</span>e<span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">setState</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
      inputValue<span class="token punctuation">:</span> e<span class="token punctuation">.</span>currentTarget<span class="token punctuation">.</span>value
    <span class="token punctuation">}</span><span class="token punctuation">)</span>
  <span class="token punctuation">}</span>

  handleAddClick <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span>props<span class="token punctuation">.</span><span class="token function">addTodo</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>inputValue<span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token punctuation">}</span>

  <span class="token function">render</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">return</span> <span class="token punctuation">(</span>
        <span class="token operator">&lt;</span>div<span class="token operator">></span>
          <span class="token operator">&lt;</span>input type<span class="token operator">=</span><span class="token string">"text"</span> value<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>inputValue<span class="token punctuation">}</span>
                 onChange<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>handleInputChange<span class="token punctuation">}</span>
          <span class="token operator">/</span><span class="token operator">></span>
          <span class="token operator">&lt;</span>button onClick<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>handleAddClick<span class="token punctuation">.</span><span class="token function">bind</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">}</span><span class="token operator">></span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>props<span class="token punctuation">.</span>btnText<span class="token punctuation">}</span><span class="token operator">&lt;</span><span class="token operator">/</span>button<span class="token operator">></span>
        <span class="token operator">&lt;</span><span class="token operator">/</span>div<span class="token operator">></span>
    <span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token punctuation">}</span>
<span class="token punctuation">}</span>

<span class="token keyword">export</span> <span class="token keyword">default</span> TodoInput<span class="token punctuation">;</span></code></pre>
<h2 id="ref"><a href="#ref" class="headerlink" title="ref"></a>ref</h2><blockquote>
<p><code>react</code>里面通过<code>ref</code>来获取组件或者<code>dom</code>元素，要是有<code>ref</code>之前必须先调用<code>React.createRef</code>方法来创建一个ref</p>
</blockquote>
<pre class=" language-react"><code class="language-react">import React, {createRef} from 'react';</code></pre>
<blockquote>
<p>添加todo之后获取焦点</p>
</blockquote>
<ul>
<li><p>创建ref：</p>
<p>在constructor里创建ref</p>
<pre class=" language-javascript"><code class="language-javascript"><span class="token function">constructor</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">super</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span>state <span class="token operator">=</span> <span class="token punctuation">{</span>
      inputValue<span class="token punctuation">:</span> <span class="token string">''</span>
    <span class="token punctuation">}</span>

    <span class="token comment" spellcheck="true">// 在constructor里创建ref</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span>inputDom <span class="token operator">=</span> <span class="token function">createRef</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
  <span class="token punctuation">}</span></code></pre>
</li>
<li><p>标签中进行使用</p>
<pre class=" language-javascript"><code class="language-javascript"><span class="token function">render</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">return</span> <span class="token punctuation">(</span>
        <span class="token operator">&lt;</span>div<span class="token operator">></span>
          <span class="token operator">&lt;</span>input type<span class="token operator">=</span><span class="token string">"text"</span> value<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>inputValue<span class="token punctuation">}</span>
                 onChange<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>handleInputChange<span class="token punctuation">}</span>
                 onKeyUp<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>handleKeyUp<span class="token punctuation">}</span>
                 ref<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>inputDom<span class="token punctuation">}</span>
          <span class="token operator">/</span><span class="token operator">></span>
          <span class="token operator">&lt;</span>button onClick<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>handleAddClick<span class="token punctuation">.</span><span class="token function">bind</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">}</span><span class="token operator">></span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>props<span class="token punctuation">.</span>btnText<span class="token punctuation">}</span><span class="token operator">&lt;</span><span class="token operator">/</span>button<span class="token operator">></span>
        <span class="token operator">&lt;</span><span class="token operator">/</span>div<span class="token operator">></span>
    <span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token punctuation">}</span></code></pre>
</li>
<li><p>按键方法和添加方法的实现</p>
<pre class=" language-javascript"><code class="language-javascript">handleKeyUp <span class="token operator">=</span> <span class="token punctuation">(</span>e<span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span>
    <span class="token keyword">if</span> <span class="token punctuation">(</span>e<span class="token punctuation">.</span>keyCode <span class="token operator">===</span> <span class="token number">13</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
      <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">handleAddClick</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>
  <span class="token punctuation">}</span>

  handleAddClick <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span>
    <span class="token comment" spellcheck="true">// 实际的项目中，还需要对this.state.inputValue做验证，如果验证通过，执行下面的方法</span>
    <span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>inputValue <span class="token operator">===</span> <span class="token string">''</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
      <span class="token keyword">return</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span>props<span class="token punctuation">.</span><span class="token function">addTodo</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>inputValue<span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">setState</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
      inputValue<span class="token punctuation">:</span> <span class="token string">''</span>
    <span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span>
      <span class="token keyword">this</span><span class="token punctuation">.</span>inputDom<span class="token punctuation">.</span>current<span class="token punctuation">.</span><span class="token function">focus</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span><span class="token punctuation">)</span>
  <span class="token punctuation">}</span></code></pre>
<blockquote>
<p>添加完成之后，在回调里进行获取焦点</p>
</blockquote>
</li>
</ul>
<h2 id="checkbox点击改变状态值"><a href="#checkbox点击改变状态值" class="headerlink" title="checkbox点击改变状态值"></a>checkbox点击改变状态值</h2><p><strong>TodoItem.js</strong></p>
<pre class=" language-javascript"><code class="language-javascript"><span class="token keyword">import</span> React<span class="token punctuation">,</span> <span class="token punctuation">{</span>Component<span class="token punctuation">}</span> <span class="token keyword">from</span> <span class="token string">'react'</span><span class="token punctuation">;</span>

<span class="token comment" spellcheck="true">// 空函数</span>
<span class="token keyword">const</span> noop <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span>
<span class="token punctuation">}</span>

<span class="token keyword">class</span> <span class="token class-name">TodoItem</span> <span class="token keyword">extends</span> <span class="token class-name">Component</span> <span class="token punctuation">{</span>
  handleCheckboxChange <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span>
    <span class="token keyword">const</span> <span class="token punctuation">{</span>
      onCompletedChange <span class="token operator">=</span> noop<span class="token punctuation">,</span>
      id
    <span class="token punctuation">}</span> <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span>props
    <span class="token comment" spellcheck="true">// 判断函数是否存在，这个函数存在才去执行</span>
    <span class="token function">onCompletedChange</span><span class="token punctuation">(</span>id<span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token punctuation">}</span>

  <span class="token function">render</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token comment" spellcheck="true">// 这样可以省略下面的前缀 this.props</span>
    <span class="token keyword">const</span> <span class="token punctuation">{</span>
      isCompleted<span class="token punctuation">,</span>
      title<span class="token punctuation">,</span>
    <span class="token punctuation">}</span> <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span>props
    <span class="token keyword">return</span> <span class="token punctuation">(</span>
        <span class="token operator">&lt;</span>li<span class="token operator">></span>
          <span class="token operator">&lt;</span>input type<span class="token operator">=</span><span class="token string">"checkbox"</span>
                 checked<span class="token operator">=</span><span class="token punctuation">{</span>isCompleted<span class="token punctuation">}</span>
                 onChange<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>handleCheckboxChange<span class="token punctuation">}</span>
          <span class="token operator">/</span><span class="token operator">></span>
          <span class="token operator">&lt;</span>span<span class="token operator">></span>
            <span class="token punctuation">{</span>title<span class="token punctuation">}</span> <span class="token punctuation">{</span>isCompleted <span class="token operator">?</span> <span class="token string">'已完成'</span> <span class="token punctuation">:</span> <span class="token string">'未完成'</span><span class="token punctuation">}</span>
          <span class="token operator">&lt;</span><span class="token operator">/</span>span<span class="token operator">></span>
        <span class="token operator">&lt;</span><span class="token operator">/</span>li<span class="token operator">></span>
    <span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token punctuation">}</span>
<span class="token punctuation">}</span>

<span class="token keyword">export</span> <span class="token keyword">default</span> TodoItem<span class="token punctuation">;</span></code></pre>
<p><strong>TodoList/index.js</strong></p>
<pre class=" language-javascript"><code class="language-javascript"><span class="token keyword">import</span> React<span class="token punctuation">,</span> <span class="token punctuation">{</span>Component<span class="token punctuation">}</span> <span class="token keyword">from</span> <span class="token string">'react'</span><span class="token punctuation">;</span>
<span class="token keyword">import</span> TodoItem <span class="token keyword">from</span> <span class="token string">'./TodoItem'</span>
<span class="token keyword">import</span> PropTypes <span class="token keyword">from</span> <span class="token string">'prop-types'</span><span class="token punctuation">;</span>

<span class="token keyword">class</span> <span class="token class-name">TodoList</span> <span class="token keyword">extends</span> <span class="token class-name">Component</span> <span class="token punctuation">{</span>

  <span class="token keyword">static</span> propTypes <span class="token operator">=</span> <span class="token punctuation">{</span>
    todos<span class="token punctuation">:</span> PropTypes<span class="token punctuation">.</span><span class="token function">arrayOf</span><span class="token punctuation">(</span>PropTypes<span class="token punctuation">.</span><span class="token function">shape</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
      id<span class="token punctuation">:</span> PropTypes<span class="token punctuation">.</span>number<span class="token punctuation">.</span>isRequired<span class="token punctuation">,</span>
      title<span class="token punctuation">:</span> PropTypes<span class="token punctuation">.</span>string<span class="token punctuation">.</span>isRequired<span class="token punctuation">,</span>
      isCompleted<span class="token punctuation">:</span> PropTypes<span class="token punctuation">.</span>bool<span class="token punctuation">.</span>isRequired
    <span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">.</span>isRequired<span class="token punctuation">,</span>

    onCompletedChange<span class="token punctuation">:</span> PropTypes<span class="token punctuation">.</span>func
  <span class="token punctuation">}</span>

  <span class="token function">render</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">return</span> <span class="token punctuation">(</span>
        <span class="token operator">&lt;</span>ul<span class="token operator">></span>
          <span class="token punctuation">{</span>
            <span class="token keyword">this</span><span class="token punctuation">.</span>props<span class="token punctuation">.</span>todos<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span>todo <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span>
              <span class="token keyword">return</span> <span class="token punctuation">(</span>
                  <span class="token operator">&lt;</span>TodoItem
                      onCompletedChange<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>props<span class="token punctuation">.</span>onCompletedChange<span class="token punctuation">}</span>
                      key<span class="token operator">=</span><span class="token punctuation">{</span>todo<span class="token punctuation">.</span>id<span class="token punctuation">}</span>
                      <span class="token punctuation">{</span><span class="token operator">...</span>todo<span class="token punctuation">}</span>
                  <span class="token operator">/</span><span class="token operator">></span>
              <span class="token punctuation">)</span>
            <span class="token punctuation">}</span><span class="token punctuation">)</span>
          <span class="token punctuation">}</span>
        <span class="token operator">&lt;</span><span class="token operator">/</span>ul<span class="token operator">></span>
    <span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token punctuation">}</span>
<span class="token punctuation">}</span>

<span class="token keyword">export</span> <span class="token keyword">default</span> TodoList<span class="token punctuation">;</span></code></pre>
<p><strong>App.js</strong></p>
<pre class=" language-javascript"><code class="language-javascript"><span class="token keyword">import</span> React<span class="token punctuation">,</span> <span class="token punctuation">{</span>Component<span class="token punctuation">,</span> Fragment<span class="token punctuation">}</span> <span class="token keyword">from</span> <span class="token string">'react'</span><span class="token punctuation">;</span>
<span class="token keyword">import</span> <span class="token punctuation">{</span>Like<span class="token punctuation">,</span> TodoHeader<span class="token punctuation">,</span> TodoInput<span class="token punctuation">,</span> TodoList<span class="token punctuation">}</span> <span class="token keyword">from</span> <span class="token string">'./components'</span><span class="token punctuation">;</span>

<span class="token keyword">class</span> <span class="token class-name">App</span> <span class="token keyword">extends</span> <span class="token class-name">Component</span> <span class="token punctuation">{</span>

  <span class="token function">constructor</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">super</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span>state <span class="token operator">=</span> <span class="token punctuation">{</span>
      title<span class="token punctuation">:</span> <span class="token string">'代办事项列表'</span><span class="token punctuation">,</span>
      desc<span class="token punctuation">:</span> <span class="token string">'今日事，今日毕'</span><span class="token punctuation">,</span>
      todos<span class="token punctuation">:</span> <span class="token punctuation">[</span><span class="token punctuation">{</span>
        id<span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">,</span>
        title<span class="token punctuation">:</span> <span class="token string">'吃饭'</span><span class="token punctuation">,</span>
        assignee<span class="token punctuation">:</span> <span class="token string">'wujie'</span><span class="token punctuation">,</span>
        isCompleted<span class="token punctuation">:</span> <span class="token boolean">true</span>
      <span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token punctuation">{</span>
        id<span class="token punctuation">:</span> <span class="token number">2</span><span class="token punctuation">,</span>
        title<span class="token punctuation">:</span> <span class="token string">'睡觉'</span><span class="token punctuation">,</span>
        assignee<span class="token punctuation">:</span> <span class="token string">'virus'</span><span class="token punctuation">,</span>
        isCompleted<span class="token punctuation">:</span> <span class="token boolean">false</span>
      <span class="token punctuation">}</span><span class="token punctuation">]</span>
    <span class="token punctuation">}</span>
  <span class="token punctuation">}</span>

  addTodo <span class="token operator">=</span> <span class="token punctuation">(</span>todoTitle<span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span>
    <span class="token comment" spellcheck="true">// 这是正确的写法</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">setState</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
      todos<span class="token punctuation">:</span> <span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>todos<span class="token punctuation">.</span><span class="token function">concat</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
        id<span class="token punctuation">:</span> Math<span class="token punctuation">.</span><span class="token function">random</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
        title<span class="token punctuation">:</span> todoTitle<span class="token punctuation">,</span>
        isCompleted<span class="token punctuation">:</span> <span class="token boolean">false</span>
      <span class="token punctuation">}</span><span class="token punctuation">)</span>
    <span class="token punctuation">}</span><span class="token punctuation">)</span>
  <span class="token punctuation">}</span>

  onCompletedChange <span class="token operator">=</span> <span class="token punctuation">(</span>id<span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span>
    console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'onCompletedChange'</span><span class="token punctuation">,</span> id<span class="token punctuation">)</span><span class="token punctuation">;</span>

    <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">setState</span><span class="token punctuation">(</span><span class="token punctuation">(</span>prevState<span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span>
      <span class="token keyword">return</span> <span class="token punctuation">{</span>
        todos<span class="token punctuation">:</span> prevState<span class="token punctuation">.</span>todos<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span>todo <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span>
          <span class="token keyword">if</span> <span class="token punctuation">(</span>todo<span class="token punctuation">.</span>id <span class="token operator">===</span> id<span class="token punctuation">)</span> <span class="token punctuation">{</span>
            todo<span class="token punctuation">.</span>isCompleted <span class="token operator">=</span> <span class="token operator">!</span>todo<span class="token punctuation">.</span>isCompleted
          <span class="token punctuation">}</span>
          <span class="token keyword">return</span> todo<span class="token punctuation">;</span>
        <span class="token punctuation">}</span><span class="token punctuation">)</span>
      <span class="token punctuation">}</span>
    <span class="token punctuation">}</span><span class="token punctuation">)</span>
  <span class="token punctuation">}</span>

  <span class="token function">render</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">return</span> <span class="token punctuation">(</span>
        <span class="token operator">&lt;</span>Fragment<span class="token operator">></span>
          <span class="token operator">&lt;</span>TodoHeader desc<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>desc<span class="token punctuation">}</span> x<span class="token operator">=</span><span class="token punctuation">{</span><span class="token number">1</span><span class="token punctuation">}</span> y<span class="token operator">=</span><span class="token punctuation">{</span><span class="token number">2</span><span class="token punctuation">}</span><span class="token operator">></span>
            <span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>title<span class="token punctuation">}</span>
          <span class="token operator">&lt;</span><span class="token operator">/</span>TodoHeader<span class="token operator">></span>
          <span class="token operator">&lt;</span>TodoInput addTodo<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>addTodo<span class="token punctuation">}</span><span class="token operator">/</span><span class="token operator">></span>
          <span class="token operator">&lt;</span>TodoList
              todos<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>todos<span class="token punctuation">}</span>
              onCompletedChange<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>onCompletedChange<span class="token punctuation">}</span>
          <span class="token operator">/</span><span class="token operator">></span>

          <span class="token operator">&lt;</span>Like<span class="token operator">/</span><span class="token operator">></span>

        <span class="token operator">&lt;</span><span class="token operator">/</span>Fragment<span class="token operator">></span>
    <span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token punctuation">}</span>
<span class="token punctuation">}</span>

<span class="token keyword">export</span> <span class="token keyword">default</span> App<span class="token punctuation">;</span></code></pre>
<p>效果截图：</p>
<p><img src="https://cdn.nlark.com/yuque/0/2020/png/1242036/1586836420359-775b02b2-6aef-481b-8853-5b6b8196c78b.png" alt="checkbox点击事件"></p>

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